How do I find the slope or cone in Fourier Domain for moving images

Reference Image I am translating this shown image by 10 pixels horizontally and 10 pixels vertically and linearly increasing the amount of pixels I am translating for four images (Eg.: (10,10), (20,20), (30,30), (40,40).

In addition, between the two images, I am having apparent motion of the snow. (I couldn’t attach as a GIF but the idea is that different part of images are moving differently).

I am taking Fourier of all images and I want to define slope that represents the apparent motion in an image and the motion due to my translation separately for each images. I understand we can find a cone that represents motion for multiple images, but that seems more complicated. I have successfully implemented till finding Fourier images but I am unable to define slope. Any help would be appreciated.

I find the following answers Answer1 very helpful Answer 2 but unlike the answers, my image doesn’t have a slope in it, but only in Fourier domain.